HarmonyOS 关于ArkTS UI样式文件的疑问

//定义样式文件，MyImageModifier .ets  
import { ImageModifier } from “@ohos.arkui.modifer”;  
class MyImageModifier extends ImageModifier {  
  public syncModeValue?: boolean  
  public cacheModeValue?: boolean  
  override applyNormalAttribute(instance: ImageAttribute): void {  
    super.applyNormalAttribute(instance)  
    // extend logics  
  }  
  syncMode(isSync: boolean) : MyImageModifier {  
    this.syncModeValue = isSync  
    return this  
  }  
  cacheMode(isCached: boolean) : MyImageModifier {  
    this.cacheModeValue = isCached  
    return this  
  }  
}  
//封装自定义组件@Component  
struct MyImage {  
  @Link modifier: MyImageModifier  
  @State src: string  
  build() {  
    Image(this.src)  
      .attributeModifier(this.modifier)  
  }  
  aboutToAppear() {  
    if (this.modifier.syncModeValue) {  
      // do something  
    }  
    if (this.modifier.cacheModeValue) {  
      // do something  
    }  
  }  
}  
//使用自定义组件  
@Entry @Component  
struct Index {  
  @State myImageModifier: MyImageModifier =  
    new MyImageModifier()  
      .syncMode(true)  
      .cacheMode(true)  
      .autoResize(true)  
      .renderMode(ImageRenderMode.Template)  
      .width(100)  
  isSync: boolean = false  
  
  build() {  
    Row() {  
      MyImage({ modifier: this.myImageModifier, src: $r(‘xxxx’) })  
      Button(“Click”).onClick(() => {  
        isSync = !isSync  
        this.myImageModifier.syncMode(isSync)  
      })  
    }  
  }  
}